Milo and Oscar learn that Bea is having a fun girls-only party and are sad that they aren't allowed to attend. To make sure they don't lose their friend forever, the boys decide to infiltrate the party (dressed as girls) and spy on everyone. When Bea and the girls realise what Milo and Oscar are up to, they make sure the boys know what it's like to be "one of the girls".

"It's a girls sleepover party, so by definition, it's girls-only!"[edit]

Bud is sleeping at his desk, with his headphones on. In Freshwater High, Mr. Baldwin announces that his class will be given a "treat": a lecture on the history of lectures. The class groan. Mr. Baldwin starts reading the book on the history of lectures, when Milo says to his brother, Oscar, that he can't concentrate on the lesson because Mr. Baldwin's nose looks like a sea cucumber, which makes him hungry. As soon as Oscar looks at Baldwin's nose, his stomach growls. Mr. Baldwin then falls asleep in the middle of reading the book. While Milo talks to his brother about "Friday Night Fun", Bea looks over the checklist for the sleepover party she's holding. The friends cheer that it's going to be the best sleepover party ever, when Milo jumps onto Bea's desk and says that she should join him and Oscar at the Hokey Poke Diner before Mr. Baldwin wakes up. Bea then says that she's throwing a "little party", and Milo says that he loves parties, thinking he's invited. Bea then says it's a special kind of party, and Milo says he's a special kind of guy. Bea then says that it's a girls-only sleepover, and says that she'll hang with Milo and Oscar tomorrow. Shellsea says it's nothing personal and sometimes the girls just need a night to get together and have fun. Milo then begs for Bea to let him come to the party. Shellsea then says she's watching Milo, with her fish eyes. The girls then leave, with Shellsea squashing her mouth to let her eyes expand. Oscar then says it's a date and he'll see her tomorrow. He then realizes what he's just said, and says not a date date because who would want that. Milo says that it's serious and explains: "Bea is throwing a party, without us". Oscar says he knows. Milo then wonders if Bea has an amazing time at the party, forgets they exist, and moves to Fishostin, Texas, gets married and has eight kids. Oscar says that Milo has completely lost his mind, when he realizes that "Bea's married and has eight kids". Milo continues wondering, and says she sells real estates. Oscar says it can't happen and they have to get Bea back. Oscar asks Milo what they should do when their stomachs growl, and Milo suggests going to the Hokey Poke Diner, as they can't think on an empty stomach.

"I am not dressing like a girl, Milo! I can't believe I'm dressed like a girl, Milo!"[edit]

Bea opens the door at her tank, and her friends are there. They all "hey" and "what", then giggle. Bea announces that they should all get down to serious girl business. Clamantha asks if anyone wants to paint her nails, and Finberley corrects her by saying that she doesn't have any nails. Shellsea responds saying that none of them do. Koi then holds up some real nails as a joke and they all giggle. At the Hokey Poke, Oscar and Milo are trying to think of ways to get into the sleepover party (and talking about letting 'the honey river' flow). Oscar compliments Bassy's hair, in which she runs away crying when she realizes it's a growth. Oscar thinks that all women want to get away from them and he and Milo are cursed in their male bodies, Milo suddenly thinks of an idea: to dress up like girls and sneak into the party, much to Oscar's dismay. Even though Oscar doesn't want to, they both end up in girl clothes. Oscar wants to go home and not be embarrassed, but Milo stops him. Oscar tells Milo not to interrupt Bea, as it looks like she's having a good time. Milo tells Oscar that Bea and her friends are laughing at them, and as they can't hear them, Milo translates through lip-reading: "Who thinks Oscar and Milo are total lamos, who we should never hang out with?". Oscar doesn't believe Milo, but when the girls put their hands up in the air, Oscar changes his mind. In the tank, Bea and her friends are actually looking for dry fin. Oscar says to Milo that they're going in. Milo rings the doorbell. Shellsea tells Bea that the doorbell has rung and Bea thought that everyone was already at the sleepover. Bea opens the door, and Shellsea "ews" at Milo and Oscar's disguises. Milo introduces himself at Milovia, and Oscar introduces himself as Oscarlinabeth. The two tell Bea and Shellsea that they are there for girls night, and swim in.

"You say that you are girls, with your front down greasy curls. But if that's true, then prove it boo, and show us what girls do!"[edit]

Oscar and Milo think that they've fooled the girls, but Bea knows that it's Milo and Oscar. Bea is irritated, because she spends every day with them and she wanted one night just with the girls. Bea doesn't know why they feel need to crash her party. Shellsea thinks that the boys have crashed their party because they are spying on them. Oscar and Milo are giggling. Bea goes over to tell them to leave, but Shellsea stops her. Shellsea says that if the boys are ruining the girls' night, then the girls should try to ruin the boys' night. Bea doesn't know if she can do it, because Oscar and Milo are just being dorks, and she can't really help it. Shellsea says it's wrong because they say that do be a girl, all you have to do is put on a dress. Bea says it's so much more than that and they have no idea what girls go through: the pain, the stress, the trials, the tribulation, and decide to teach the boys a lesson. Shellsea "likes it". Bea tells all the girls which aren't boys to huddle up. Oscar and Milo stay put where they are as they're boys. Bea tells her friends that girls night has been infiltrated by boys. Koi makes angry sounds, and Bea says that she's angry too and Oscar and Milo chose the wrong girls night to crash. Oscar asks Shellsea why she looks mad, and responds with saying it's just her face. Milo then shows the girls his "girl face". Milo and Oscar agree to having a makeover and Koi takes them over to get a facial: blasting Oscar and Milo in the face with water, pounding their heads in the mud, and Clamantha launching pearls onto their faces. The girls then perform Eat Dip!. Milo tells Oscar that it could take years to win Bea back. Shocked at this, Oscar tells everyone to stop. Milo stops Oscar and asks Oscar what he is doing. Oscar's tired of the lies and wants Bea to appreciate them for the men they are. Milo begs Oscar not to reveal that they're boys, but Oscar does it and tells the girls to judge them for not being honest fish. Oscar starts crying and asks them why they aren't acting angry-mob style. Bea then tells them the girls already knew that they were boys. Milo and Oscar are confused why they knew, and the girls tell them that they're not idiots. Shellsea announces that the girls were messing with them because they were 'spying'. Milo tells them that they thought him and Oscar were going to lose Bea if they didn't show their feminine sides. All the other girls "aw". Bea is touched as Oscar and Milo did all the dressing-up like girls thing for her. Milo suggests having a pillow fight, but Bea kicks him and Oscar out. Milo and Oscar decide to have a boys sleepover with Jocktopus, but since the two kicked Jocktopus during the song, he decides to strangle them. Oscar wants to be a girl again.

Snake: All this talk about parties, so makes me wanna have a party. Mouse: A party? We can't have a party in here. This terrarium is like, 8 in. by a foot and 1/2. We don't even fit in here. Snake: Oh, I kinda already invited everyone. Mouse: What do you mean, everyone? (Snake hears a buzzer) Snake: Door's open, come on up! Mouse: We need a bigger terrarium. (Mouse laughs) End